In the construction of modern day cab assemblies, it is common practice to build the cab around a very structurally sound framework. The framework is intended to withstand tremendous forces that would be applied to the cab in the event that the vehicle to which the cab was attached should happen to roll over. This structure must be able to withstand forces at least equal to the weight of the vehicle to prevent the occupant of the cab from being crushed as as the vehicle rolls over. This structure is commonly known as a rollover protective structure or ROPS.
The rollover protective structures are normally comprised of a plurality of tubular posts that are usually fixed together by welding. They normally consist of an upper rectangular section and a lower rectangular section that are joined by vertical posts that extend between the corners of the respective rectangular sections. Because the corner area joins three structural members that extend in three separate directions, it is inherently the weakest member of the structure. As a result, it must be heavily braced. Each corner member normally includes as many as six braces that extend between the individually directed structural members. This not only increases the complexity of the ROPS, it also increases the number of parts as well as the time required to fabricate the assembly.
In other instances, the rollover structure includes a pair of fabricated posts that have sufficient cross-sectional area to withstand the forces that would be applied to the structure in the event of a vehicle rollover. These types of structures have been known to include areas that have thinner cross-sections at preselected locations to allow a predetermined amount of plastic deformation. One such design is disclosed in U.S. Pat. No. 3,591,668, issued to Stanley B. Adams on Feb. 12, 1974. This design utilizes fabricated upright leg members that extend upwardly from the vehicle frame along each side of the vehicle. The leg members define upper and lower transition areas, or areas of reduced cross-section, to define plastically deformable hinge points upon application of forces that exceed a predetermined magnitude. In order to create these transition areas, the ROPS must be fabricated in such a manner to insure that the portion of the leg members immediately above and below the transition areas have a more rigid structure. In order to provide this rigidity, the structure utilizes several transverse and longitudinal brace assemblies. While this particular design has been known to work quite well in its intended capacity, it inherently requires many components and substantial time to fabricate and assemble the components.
The present invention is directed to overcoming one or more of the problems set forth above.